The present invention relates to an automatic record player changer and, more particularly, to an automatic record player having a so-called umbrella type spindle in which holder claws for holding record discs are adapted to retract into and extend out of a slit formed in the spindle body through up and down movement of a spindle shaft accommodated in the spindle body.
The invention aims at providing an automatic record player of this kind in which the construction thereof is simplified without being accompanied by a substantial degradation of reliability, so as to facilitate assembly and reduce manufacturing costs.
Generally speaking, changer type automatic record players are arranged such that playing continues as long as discs are set on the spindle and playing automatically stops when there are no more discs on the spindle. Various experiments and developments have been made to this end. Among many proposals which have been made concerning the technique for controlling the operation of the player upon detection of the presence of a disc on the spindle, an apparatus disclosed in Japanese Patent Publication No. 30441/74 is considered superior because of its simple construction. This apparatus has a spindle assembly consisting of a spindle body, a spindle shaft adapted to move up and down within the spindle body, holder claws adapted to retract into and extend out of the spindle body through slits formed in the latter, by the up and down movement of the spindle shaft, so as to hold and drop the record disc inserted onto the spindle . The spindle shaft is provided in its lower peripheral portion with a groove which is exposed on the spindle body when the spindle shaft has been lowered by a predetermined distance. Disposed beneath the spindle assembly are a lever adapted to be swung up and down by a driving mechanism and to make contact, when swung up, with the lower end of the spindle shaft so as to move the latter upward, and a hook pivotally mounted to the lever and adapted to engage the groove formed in the lower portion of the spindle shaft, when the lever is lowered by a predetermined distance together with the spindle shaft.
As the lever is lowered while the disc is held by the holder claws, the holder claws and the spindle shaft are lowered by a predetermined distance due to the force of gravity so that the groove formed in the lower peripheral portion of the spindle shaft appears from the lower end of the spindle body, and is engaged by the hook pivotally mounted to the lever. As the lever is further lowered, the holder claws and the spindle shaft are pulled by the hook and moved downward beyond the above-mentioned predetermined distance so that the holder claws are retracted into the spindle body through the slits. Consequently, the disc which has been held by the holder claws drops onto the turn table. However, if there is no disc held by the spindle, the holder claws and the spindle shaft are not lowered substantially, even after the lowering of the lever, because no weight of the disc is applied to the holder claw. Consequently, the hook pivots freely apart from the lower end of the spindle, and the changing operation of the player can be automatically and completely stopped by the rotation of this hook.
This apparatus, however, involves the following problem.
Namely, in order to attain the effective operation of automatic mechanisms for continuing or stopping the playing, this apparatus requires a sufficiently high precision of design and assembly, so as to obtain for example, the precise up and downward movement of the spindle shaft , the exact position of the groove, the suitable position of the hook on the lever and so forth. For this reason, no reliable operation can be expected by which such an apparatus may be used in practice.